Give him to the SPCA. Someone will adopt him and give him a loving home. Do NOT put him outdoors. He won't make it in the wild and another animal will kill him. There are many people who would be willing to take him and give him a good home. If you don't want to drop him off at the animal shelter yourself then have a friend drop the rabbit off at the animal shelter for you.

Could you please explain more? What is it that makes you upset? Has his personality changed? Is it the maintenance that you don't like? How long have you had him? What is the rabbit's age? What is it that has disappointed you? It is possible that there is an easy fix to whatever it is. It could simply be a lack of information or know-how that is causing the problem.